Radiotelephones, in order to be portable, are often powered by batteries. When the radiotelephone is bumped or dropped, the batteries lose electrical contact with the radiotelephone interrupting the power supply. This results in the radiotelephone being turned off. A number of mechanical solutions have been tried, but none have been able to eliminate this concern.
As a result a number of electronic approaches have been tried. One approach has been to always restart the radio once power is available, and use a timer to determine how long the battery or power source has been interrupted. If the power source has been interrupted for a short period of time, the radiotelephone will stay powered on. A short interruption of the power supply is assumed to be unintentional. However, if the power source has been interrupted for a long period of time, the radiotelephone is turned off. A long interruption of the power supply is assumed to be intentional. The user can be confused by this approach, since he sees his radiotelephone turn on and then turn off for no apparent reason. Another drawback of this approach is that the battery power is wasted in turning the radiotelephone on just to determine that it needs to be turned off.
Another approach has been to start a timer when the power supply is interrupted and to only attempt to restart the radiotelephone after a predetermined period of time has passed. If the power supply has been reapplied, then the radiotelephone will turn on, otherwise it will not turn on. This results in an inherent delay in restarting the radiotelephone every time the power source of the radiotelephone is interrupted. As a result incoming telephone calls may be missed. Additionally it can add delay to the start up time when the user wants to intentionally turn on the radiotelephone.
Thus there exists a need for a device which can solve these and other problems resulting from power interruptions in a radiotelephone.